Cardiovascular risk factors associated with chronic renal insufficiency in black patients as seen at the Kenyatta National Hospital

Abstract

Background: Cardiovascular disease (CVD) is a major cause of morbidity and mortality among patients with chronic renal insufficiency (CRI). CVD is actually recognised as the leading cause of mortality and morbidity in the Chronic Renal Disease population. CVD mortality is approximately 10 to 30 times higher in patients treated by dialysis compared with patients in the general population, despite stratifying for gender, race, and the presence of Diabetes. After standardising for age, CVD mortality remains 1a-fold higher in dialysis patients than in the general population, even at the extremes of age [1],[2]. The high prevalence of CVD in patients beginning dialysis suggests that CVD begins during or before the stage of CRI. Although there have been few studies of CVD in CRI, the available data suggest a higher incidence and prevalence of CVD than in the general population. No Data exists on the prevalence of cardiovascular risk factors in patients with chronic renal insufficiency at Kenyatta National Hospital. Objectives: The aim of the study was to determine the prevalence of certain established and emerging cardiovascular risk factors, specifically, cigarette smoking, obesity, hypertension, dyslipidaemias, anaemia, hyperhomocysteinaemia, poor glycaemic control and left ventricular hypertrophy, in patients with Chronic Renal Insufficiency seen at the Kenyatta National Hospital. Design: Cross-sectional prevalence study. Setting: Tertiary Hospital (Kenyatta National Hospital), specialist nephrology clinic. Patient selection: Consecutive sampling of CRI patients. CRI was defined as a calculated creatinine clearance of less than 75mls/min (documented twice at least 1 month apart, with no identifiable reversible cause. (Creatinine clearance was derived using the Cockcroft-Gault formula. [3]) Variables of interest: Age and sex, cigarette smoking, systemic arterial hypertension, obesity, anaemia, total cholesterol, LDL-cholesterol, HDLcholesterol, triglycerides, homocysteine levels, left ventricular hypertrophy, obesity, and poor glycaemic control among diabetic patients. Results: Between April and October of 2002, 83 patients with chronic renal insufficiency were studied, 59 males and 24 females. The underlying aetiology of the Renal failure was Chronic glomerulonephritis in 36.1 %, Hypertension in 31.3%, Diabetes mellitus in 28.9%, and polycystic kidney disease in 3.6%. The mean creatinine clearance was 47mls/min (95%CI 27.5-66.5mls/min) with 16.9% having a clearance less than 25mls/min, 34.9% having a clearance between 25 and 50mls/min, and 48% having a clearance between 50 and 75mls/min.62.7% of the patients had age and sex as vascular risk factors. There were 6(7.23%) current smokers, all males. The mean BMI was 23.4kg/m2 (95%CI 20.6-26.2), with 32.5% of patients being either overweight or obese. 15 of the 27 obese patients had central obesity.61.5% of patients were hypertensive, of these patients,81 % were on anti-hypertensive treatment. 4.8% of patients had elevated total cholesterol levels.12% of patients had elevated LDL-Cholesterol levels. 73(88%) patients had low HDLcholesterol levels. 13(15.7%) patients had elevated triglyceride levels. The mean Homocysteine level was 24.10mol/1 (95%CI 10.2-38). 77 patients(92.8%) had elevated homocysteine levels. The mean glycated haemoglobin level among the 24 diabetic patients was 7.43(95%CI 6-8.8), with 37.5% of patients exhibiting poor glycaemic controI.72.3% of patients had elevated blood pressures, of these patients, 81% were on anti-hypertensive therapy and demonstrated less than optimal control. The mean haemoglobin was 11.6g/dl(95%CI 9.1-14). 49 patients (59%) of patients were anaemic. Significantly, creatinine clearance was inversely co-related to haemoglobin levels (p= .01212). Male patients were more likely to be anaemic than female patients (p= .00001) there was also a significant relationship between level of blood pressure and haemoglobin level (p=. 00050). The mean left ventricular mass index was 133.6g/m2 (95% CI 94.3-172). Males were more likely to have high left ventricular mass indices (p=. 03800). There was a significant inverse relationship between creatinine clearance and left ventricular mass index (p=. 00047) Similarly, there was a significant inverse co-relation of haemoglobin level and left ventricular mass index (p<.00001 ).There was a strong relationship between level of blood pressure and left ventricular mass index (p=.00003). Multiple regression analysis revealed that the relationships of Haemoglobin level and Hypertension to left ventricular hypertrophy were independent of other variables.(p<0.0001 in both cases). 94% of patients had two or more cardiovascular risk factors. Conclusions: There is a high prevalence of cardiovascular risk factors, frequently multiple, in patients with chronic renal insufficiency seen at KNH. A significant relationship between Anaemia, hypertension and left ventricular mass index was also demonstrated.